Browsing by Subject "Power loss"
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Item Open Access Dynamical screening effects in hot-electron scattering from electron-hole plasma and LO-phonon modes in quantum wires(Elsevier, 1996) Bennett, C. R.; Tanatar, Bilal; Constantinou, N. C.We present a fully dynamical and finite temperature study of the hot-electron momentum relaxation rate and the power loss in a coupled system of electron-hole plasma and bulk LO-phonons in a quantum wire structure. Interactions of the scattered electron with neutral plasma components and phonons are treated on an equal footing within the random-phase approximation. Coupled mode effects substantially change the transport properties of the system at low temperatures. Particularly, the "plasmon-like" and "LO-phonon-like" excitations yield comparable rates which, as a consequence of the singular nature of the ID density of states, can be large at the threshold. This is in contrast to room temperature results where only the LO-phonon mode contributes significantly to the rate. The density and temperature dependence of the power loss reveals that dynamical screening effects are important, and energy-momentum conservation cannot be satisfied above a certain density for a given initial energy.Item Open Access Energy relaxation rates in AlInN/AlN/GaN heterostructures(Springer, 2012-06-27) Tiras, E.; Ardali, S.; Arslan, E.; Özbay, EkmelThe two-dimensional (2D) electron energy relaxation in Al0.83In0.17N/AlN/GaN heterostructures has been investigated experimentally. Shubnikov-de Haas (SdH) effect measurements were employed in the investigations. The electron temperature (T (e)) of hot electrons was obtained from the lattice temperature (T (L)) and the applied electric field dependencies of the amplitude of SdH oscillations. The experimental results for the electron temperature dependence of power loss are also compared with current theoretical models for power loss in 2D semiconductors. The power loss from the electrons was found to be proportional to (T (e) (3) - T (L) (3) ) for electron temperatures in the range 1.8 K < T (e) < 14 K, indicating that the energy relaxation of electrons is due to acoustic phonon emission via unscreened piezoelectric interaction. The effective mass and quantum lifetime of the 2D electrons have been determined from the temperature and magnetic field dependencies of the amplitude of SdH oscillations, respectively. The values obtained for quantum lifetime suggest that remote ionized impurity scattering is the dominant scattering mechanism in Al0.83In0.17N/AlN/GaN heterostructures.Item Open Access The static and dynamic screening of power loss of a two-dimensional electron gas(Academic Press, 1998) Bennett, C.; Balkan, N.; Tanatar, Bilal; Celik, H.; Cankurtaran, M.Experimental results concerning the well-width dependence of the acoustic-phonon-assisted energy relaxation of a two-dimensional electron gas in GaAs/Ga1-xAlxAs quantum-well structures are compared with theoretical models that involve piezoelectric and deformation-potential scattering and the effects of static and dynamic screening of the electron-acoustic phonon interaction. It is shown that screening only slightly modifies the predictions of the approximate calculations. © 1998 Academic Press.Item Open Access Temperature dependent energy relaxation time in AlGaN/AlN/GaN heterostructures(2012) Tiras, E.; Celik O.; Mutlu, S.; Ardali, S.; Lisesivdin, S.B.; Özbay, EkmelThe two-dimensional (2D) electron energy relaxation in Al 0.25Ga 0.75N/AlN/GaN heterostructures was investigated experimentally by using two experimental techniques; Shubnikov-de Haas (SdH) effect and classical Hall Effect. The electron temperature (T e) of hot electrons was obtained from the lattice temperature (T L) and the applied electric field dependencies of the amplitude of SdH oscillations and Hall mobility. The experimental results for the electron temperature dependence of power loss are also compared with the current theoretical models for power loss in 2D semiconductors. The power loss that was determined from the SdH measurements indicates that the energy relaxation of electrons is due to acoustic phonon emission via unscreened piezoelectric interaction. In addition, the power loss from the electrons obtained from Hall mobility for electron temperatures in the range T e > 100 K is associated with optical phonon emission. The temperature dependent energy relaxation time in Al 0.25Ga 0.75N/AlN/GaN heterostructures that was determined from the power loss data indicates that hot electrons relax spontaneously with MHz to THz emission with increasing temperatures. © 2012 Elsevier Ltd. All rights reserved.